U.S. Pat. No. 3,500,823 discloses electrodes for electrocardiographic and bioelectric recording. These electrodes comprise an aluminum disc with an insulating coating. The insulating coating is applied through an anodizing process. The electrodes are placed directly on the unprepared skin of the patient for recording electrocardiographic and bioelectric signals.
However, up to now these electrodes are normally not used in the field of electrophysiological sensing, because they do not fulfill the requirements with respect to hygiene.